The invention relates to a tube assembly for an optical instrument, such as a microscope, having at least two rotary joints.
From U.S. Pat. No. 4,605,287, a surgical microscope for two operators is known which includes a viewing tube for the surgeon and a second viewing tube for the assistant. The viewing tube for the assistant includes a rotary joint location, which lies perpendicular to the tube axis and about which the ocular view can be rotated by 360xc2x0 relative to the base part of the assistant viewing tube with which the assistant viewing tube is accommodated on the surgical microscope. Furthermore, the assistant viewing tube includes a further rotary joint position about which the assistant viewing tube can be rotated about the optical axis of the main viewing tube.
The rotational joints of the assistant viewing tube function so that the assistant can bring, relative to the main body of the surgical microscope, his ocular view into a position ergonomically favorable for him. Mutually conflicting requirements are present with respect to the friction forces in the rotary joints. On the one hand, the friction forces should be so high that the rotary joints stay in an adjusted position and are not pivoted into another position unintentionally because of small forces; on the other hand, in those cases, in which a changed rotation of the tube parts relative to each other is wanted, the rotation should be possible with forces as small as possible and, if possible, with one hand.
It is an object of the invention to provide a tube assembly which accommodates the above mutually opposing requirements.
The tube assembly of the invention is for an optical instrument and includes: a first rotary joint; a first brake for latching the first rotary joint; a second rotary joint; a second brake for latching the second rotary joint; an operator-controlled device operatively connected to the first and second brakes; and, the operator-controlled device being switchable between a first state wherein the first and second brakes are applied to the rotary joints and a second state wherein the first and second brakes are released to permit movement of the rotary joints.
The tube assembly of the invention includes at least two rotary joints. The rotary joints are latchable by means of brakes. A common operator lever is provided for releasing the brakes. When the operator lever is actuated, both rotary joints are enabled and, in the case of more than two rotary joints, all rotary joints are enabled.
When the operator lever is not actuated, the rotary joints are latched by the brakes. An unintended rotation of the rotary joints is thereby precluded. If, in contrast, a rotation is wanted, then the user can release the brakes. The rotary joints are no longer held when the brakes are released. For this reason, the rotation can take place with the slightest application of force. Because all brakes are released simultaneously with an actuation of the operator lever, the operating advantage results that the user must not think in advance about which rotary joint position a rotation has to take place in order to bring the ocular viewing location into the wanted position. Instead, the operator simply has to actuate the single operating lever and, thereupon, pivot the ocular viewing location into the wanted new position and then latch the brakes in this new position by releasing the operator lever.
The operator lever for the brakes is preferably mounted on the tube at the ocular end or user end.
There are various possibilities for the transmission of the movement of the operator lever. For example, an electrical transmission can be provided and, in this case, the brakes would have to be electromagnetically configured. If there is no power supply at or in the tube, the transmission of the movement of the operator lever can also take place strictly mechanically via pins and deflecting levers. The brakes themselves can then be configured to be strictly mechanical.
In a preferred embodiment of a mechanical transmission of the movement of the operator lever to the brakes, the brakes are releasable via an application of force parallel to the particular rotational axis without additional force deflection. In this way, a constructively simple solution results. In one embodiment, which requires no additional force deflection or rerouting, the brakes comprise lamellas having friction linings and entrainment means. The entrainment means of sequentially arranged lamellas alternately engage in the inner tube and the outer tube of the parts of the rotational joint, which can be rotated counter to each other. Here, it is possible to latch the various rotary joints even with different braking force in that the brakes of the various rotary joints have varying numbers of lamellas.
To generate the braking force, the braking pressure is applied to the brakes or the pins preferably by means of one or more pressure springs.
In an alternate embodiment of the brakes, rollers are provided between the inner tube and the outer tube of each rotary joint and the axes of the rollers extend parallel to the tube axis. The rollers are pressed against the inner tube by springs along a V-shaped surface on the outer tube. The pins have inclined surfaces in the region of the rollers for releasing the brakes. Because of these surfaces, the rollers are pressed toward the outside against the force of the pressure springs with the activation of the operator lever. Clamping-roller free-running brakes of this kind make possible extremely high holding forces and are free of play but lead also to high radial forces on the bearing locations of the rotary joints. Furthermore, the holding forces cannot be metered and a rotation of the rotary joint is virtually precluded when the brakes are latched and it is not easily possible to provide varying braking forces for the different rotary joints.